Field of the Invention
The invention relates industrial fastening techniques such as used in construction, such as lightweight construction, machine construction, automotive and aircraft construction and furniture industry.
Description of Related Art
Lightweight building boards consist of two outer, relatively thin cover layers, for example particleboards, and a filling, for example a honeycomb structure made of card, arranged between the cover layers. Lightweight building boards of this type are mechanically very stable, lightweight, and can look attractive if the edges are finished neatly. Specifically because of their low weight and also because of the low consumption of resources in their production, they are becoming increasingly popular.
Edges (decorative edges) for such lightweight building boards are, for example, plastic strips sealed on the outer surface and provided with a suitable decoration, and may furthermore be provided with an adhesive on the rear side. Decorative edges formed as veneer edges are also available.
However, finishing the edges in such a way as to obtain an attractive appearance has, to some extent, not yet been satisfactorily accomplished. In particular for the production of ready-made and mass-produced products, it would be desirable if a cut-to-size lightweight building board could be provided with an edge by a craftsman after the cutting-to-size operation, without involving great effort and using available tools.
For the secure fastening of the edge, the prior art discloses on the one hand the provision of a so-called crosspiece, that is a particle profile completely filling the intermediate space between the cover layers in the region of the edge. A commercially available edge of the desired type can then be adhesively attached to such a crosspiece. Such crosspieces are mechanically very stable. However, they contribute significantly to the overall weight of the board and can only be retrofitted with considerable effort. They are therefore suitable in particular for fitting at the time that the lightweight building board is made, and consequently particularly for industrial production.
On the other hand, so-called support edges are known. These are plastic strips or plastic laths which are attached to the edge between the cover layers, the cover layers generally also being milled on the inside. The actual edge with the decoration is then glued onto this support edge. The document EP 1 640 128 shows as a method in which the edge is glued onto the support edge before the support edge is attached.
The support edge technique is also quite laborious and necessitates the use of machines especially provided for the support edges. For anything other than industrial production, their use entails disadvantages and is even virtually impossible.
Other lightweight construction elements comprise sandwich boards of composite cover layers and filling layers of a suitable material, such as a foam (metal foam, polymeric foame, etc.). Also for these materials, there exists the challenge of efficiently and reliably attaching an edge structure to the construction element.
Similar problems arise if a construction element does not have discrete, distinct layers (cover layers, filling layer) but is composed of a material composition having a continuous density profile, with denser outer regions and a less dense inner region. An edge structure may be desireable also for such construction elements, for aesthetic reasons and/or for protection, for example against humidity.